The narrowing or blockage of arteries, which results in obstructions to blood flow, may cause an insufficient supply of oxygen to body tissues, which may ultimately lead to loss of function of these tissues. These obstructions may occur when a blood clot or a fatty deposit arrive from a first artery through the bloodstream (e.g., from the aorta) and settle in a portion of a second artery, thereby causing narrowing or blockage of the second artery. Alternatively, an obstruction may be generated from the formation of a blood clot in the artery itself, usually where the artery has been damaged due to a disease of the artery. Causes for such damage may be a medical procedure, atherosclerosis, inflammation of the artery, or an aneurysm.
In addition, blood flow in an artery may be low due to a patient having a weak heart, e.g., due to the patient suffering from heart failure, due to nerve damage, or due to other factors.